Such a trench-box is used to short up the walls of an excavation.
This invention is one of two inventions which are the subject of two co-pending patent applications both filed on the same day by the present applicant. The other patent application is as follows:
PAT. application No. 07-518,692 entitled "CONNECTION BETWEEN PANELS IN A TRENCH-BOX".
A trench-box panel has to be strong enough to withstand quite severe usage in civil engineering work involving excavation. Quite often, workmen resort to using a mechanical digger to knock a panel into an excavation and to move the panel into position against a wall of the excavation, hitting the panel first on one end and then on the other end of the panel until it is correctly positioned. The struts are extended to force the panel against the wall of an excavation, with a loading which may be as much as 40 kN/M.sup.2 (kilonewtons per square meter). A trench-box panel is required to be re-useable in one excavation after another. It is also required to be light enough in weight for transportation and manoeuvering into position on site.